This section is intended to provide a background or context to the invention that is recited in the claims. The description herein may include concepts that could be pursued, but are not necessarily ones that have been previously conceived or pursued. Therefore, unless otherwise indicated herein, what is described in this section is not prior art to the description and claims in this application and is not admitted to be prior art by inclusion in this section.
Various technologies for providing three-dimensional (3D) video content are currently investigated and developed. Especially, intense studies have been focused on various multiview applications wherein a viewer is able to see only one pair of stereo video from a specific viewpoint and another pair of stereo video from a different viewpoint. One of the most feasible approaches for such multiview applications has turned out to be such wherein only a limited number of input views, e.g. a mono or a stereo video plus some supplementary data, is provided to a decoder side and all required views are then rendered (i.e. synthesized) locally by the decoder to be displayed on a display.
Several technologies for view rendering are available, and for example, depth image-based rendering (DIBR) has shown to be a competitive alternative. A typical implementation of DIBR takes stereoscopic video and corresponding depth information with stereoscopic baseline as input and synthesizes a number of virtual views between the two input views. Thus, DIBR algorithms may also enable extrapolation of views that are outside the two input views and not in between them. Similarly, DIBR algorithms may enable view synthesis from a single view of texture and the respective depth view.
Some video coding standards introduce headers at slice layer and below, and a concept of a parameter set at layers above the slice layer. An instance of a parameter set may include all picture, group of pictures (GOP), and sequence level data such as picture size, display window, optional coding modes employed, macroblock allocation map, and others. Each parameter set instance may include a unique identifier. Each slice header may include a reference to a parameter set identifier, and the parameter values of the referred parameter set may be used when decoding the slice. Parameter sets decouple the transmission and decoding order of infrequently changing picture, GOP, and sequence level data from sequence, GOP, and picture boundaries. Parameter sets can be transmitted out-of-band using a reliable transmission protocol as long as they are decoded before they are referred. If parameter sets are transmitted in-band, they can be repeated multiple times to improve error resilience compared to conventional video coding schemes. The parameter sets may be transmitted at a session set-up time. However, in some systems, mainly broadcast ones, reliable out-of-band transmission of parameter sets may not be feasible, but rather parameter sets are conveyed in-band in Parameter Set NAL units.